The conference comes at a time when scientists increasingly say they have powerful new tools to add to tried-and-true condoms.

Studies show treatment-as-prevention, treating HIV right away rather than after someone is sick, lowers patients' chances of spreading the virus through sex by a stunning 96 percent. Already, Fauci said regions that are pushing to get more people tested and rushed into treatment are starting to see infections drop, from San Francisco and Washington to part of South Africa.

The U.S. Food and Drug Administration just approved use of a daily AIDS medicine, Truvada, for use by healthy people hoping to lower the risk of infection by a sexual partner. Hard-hit poor countries are grappling with how to get that protection to their highest-risk populations.

Other goals include getting more HIV-infected pregnant women treated to protect their babies, and getting more men circumcised in developing countries to protect them from heterosexual infection.

But the hurdles are huge.

Since the first reports of AIDS surfaced 31 years ago, a staggering 30 million people have died from the virus and 34.2 million now are living with HIV around the world.

There's still no cure and no vaccine. For every person who starts treatment, two more are becoming infected.

In poor countries, a record 8 million people are getting HIV drugs, but the United Nations says it will take up to $24 billion a year - $7 billion more than is being spent now - to reach those most in need.

The epidemic is worst in developing countries, especially in Africa. Progress has stalled even in the U.S., which has seen about 50,000 new infections every year for a decade. Here, nearly 1.2 million people live with HIV, and one in five don't know it.